Heretofore, there have been known antivibration devices wherein an antivibration base body constituted by a rubber-like elastic body couples an inner sleeve and an outer sleeve. Of the antivibration devices, there is one wherein the outer sleeve is press-fitted in a bracket on a vibration source side or the like to be secured and wherein the inner sleeve is secured by bolts or the like to mating members of a vibration receiving side or the like (Patent Literature 1). An annular stopper is fitted on one end portion of the inner sleeve, so that the collision between an end portion of the outer sleeve and the mating member is cushioned by the stopper. Patent Literature 1 describes that in order to make the stopper difficult to come off the inner sleeve until the inner sleeve is secured to the mating members, one end portion of the inner sleeve is expanded in diameter after the stopper is fitted on the one end portion of the inner sleeve.